Debian GNU/Linux installation notes

Unofficial builds from third-parties are not supported here. Any bugs
should be reported to the Debian team unless they can be reproduced using
the latest builds from our » download
area.

While the instructions for building PHP on Unix apply to Debian as well,
this manual page contains specific information for other options, such as
using either the apt-get or aptitude
commands. This manual page uses these two commands interchangeably.

Using APT

First, note that other related packages may be desired like
libapache2-mod-php5 to integrate with Apache 2, and
php-pear for PEAR.

Second, before installing a package, it's wise to ensure the package list
is up to date. Typically, this is done by running the command
apt-get update.

Example #1 Debian Install Example with Apache 2

# apt-get install php5-common libapache2-mod-php5 php5-cli

APT will automatically install the PHP 5 module for Apache 2 and all of its
dependencies, and then activate it. Apache should be restarted in order for
the changes take place. For example:

Example #2 Stopping and starting Apache once PHP is installed

# /etc/init.d/apache2 stop
# /etc/init.d/apache2 start

Better control of configuration

In the last section, PHP was installed with only core modules. It's
very likely that additional modules will be desired, such as
MySQL,
cURL,
GD,
etc. These may also be installed via the apt-get command.

The examples will show a lot of packages including several PHP specific ones
like php5-cgi, php5-cli and php5-dev. Determine which are needed
and install them like any other with either apt-get
or aptitude. And because Debian performs
dependency checks, it'll prompt for those so for example to install
MySQL and cURL:

Example #4 Install PHP with MySQL, cURL

# apt-get install php5-mysql php5-curl

APT will automatically add the appropriate lines to the
different php.ini related files like
/etc/php5/apache2/php.ini,
/etc/php5/conf.d/pdo.ini, etc. and depending on
the extension will add entries similar to extension=foo.so.
However, restarting the web server (like Apache) is required before these
changes take affect.

Common Problems

If the PHP scripts are not parsing via the web server, then it's
likely that PHP was not added to the web server's configuration
file, which on Debian may be /etc/apache2/apache2.conf
or similar. See the Debian manual for further details.

If an extension was seemingly installed yet the functions are undefined,
be sure that the appropriate ini file is being loaded and/or the web
server was restarted after installation.

There are two basic commands for installing packages on Debian (and other
linux variants): apt-get and aptitude.
However, explaining the subtle differences between these commands goes
beyond the scope of this manual.